linux-kernel - ntp audit spew.

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Message-ID: <20190923155041.GA14807@codemonkey.org.uk>
Date:   Mon, 23 Sep 2019 11:50:41 -0400
From:   Dave Jones <davej@...emonkey.org.uk>
To:     Linux Kernel <linux-kernel@...r.kernel.org>
Cc:     Paul Moore <paul@...l-moore.com>, Eric Paris <eparis@...hat.com>
Subject: ntp audit spew.

I have some hosts that are constantly spewing audit messages like so:

[46897.591182] audit: type=1333 audit(1569250288.663:220): op=offset old=2543677901372 new=2980866217213
[46897.591184] audit: type=1333 audit(1569250288.663:221): op=freq old=-2443166611284 new=-2436281764244
[48850.604005] audit: type=1333 audit(1569252241.675:222): op=offset old=1850302393317 new=3190241577926
[48850.604008] audit: type=1333 audit(1569252241.675:223): op=freq old=-2436281764244 new=-2413071187316
[49926.567270] audit: type=1333 audit(1569253317.638:224): op=offset old=2453141035832 new=2372389610455
[49926.567273] audit: type=1333 audit(1569253317.638:225): op=freq old=-2413071187316 new=-2403561671476

This gets emitted every time ntp makes an adjustment, which is apparently very frequent on some hosts.

Audit isn't even enabled on these machines.

# auditctl -l
No rules

# auditctl -s
enabled 0
failure 1
pid 0
rate_limit 0
backlog_limit 64
lost 0
backlog 0
loginuid_immutable 0 unlocked

Asides from the log spew, why is this code doing _anything_ when audit
isn't enabled ?

Something like this:

diff --git a/kernel/audit.c b/kernel/audit.c
index da8dc0db5bd3..1291d826c024 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -2340,6 +2340,9 @@ void audit_log(struct audit_context *ctx, gfp_t gfp_mask, int type,
 	struct audit_buffer *ab;
 	va_list args;

+	if (audit_initialized != AUDIT_INITIALIZED)
+		return;
+
 	ab = audit_log_start(ctx, gfp_mask, type);
 	if (ab) {
 		va_start(args, fmt);

Might silence the spew, but I'm concerned that the amount of work that
audit is doing on an unconfigured machine might warrant further
investigation.

("turn off CONFIG_AUDIT" isn't an option unfortunately, as this is a
one-size-fits-all kernel that runs on some other hosts that /do/ have
audit configured)

	Dave